Girassol Oil Field in Lower Congo Basin, located at offshore Block 17 with water depth of 1250～1400m, is 150km far from the coast of Angola in Africa.. It was discovered by ELF Corp. in 1996 and oil (light oil) yield began in late 2001. It is the first deepwater field that was put into production in Angola. The field covers an area of about 140km2 and has about 1550 MMBO of oil reserves in-place and estimated 725 MMBO of recoverable reserves. Corresponding to three tectonic evolution stages of rifting, transition and thermal depression undergone in Lower Congo Basin, continental, evaporite and marine sequences deposited. Lower Cretaceous Bucomazi lacustrine shale is the excellent source rock with a high TOC value and moderate maturity (Type-Ⅰ kerogen). Main reservoir is the Upper Oligocene-Miocene superimposed turbiditic complex interbedded with several thin-layered sandstone and marine mudstone and shale in channels.The reservoir is characteristic of good property due to poorly-consolidated sandstone.